Return flow carburetor



Jan. 12, 1965 T. M. BALL RETURN now CARBURETOR' 2 Sheets-Sheet 1 Filed July 28. 1959 .9 4 55 INVENTOR.

7kamaj M 23422.

BYALE Jan. 12, 1965 T. M. BALL 3,165,561

RETURN now CARBURETOR Filed July 28. 1959 2 Sheets-Sheet 2 United States Patent 3,165,561 RETURIJ FILGW Thomas M. Ball, Bloomfield Hills, Mich, ass'gnor to Chrysler Qorporation, Highland Paris, Misha, a corporation of Delaware Filed duly 28, 195?, der. No. 33%,l24 7 Claims. (6i. 262-27} This invention relates to improvements in a carburetor particularly adapted for use with an automobile internal combustion engine. This application is a continuation-inpart of my co-pending application Serial No. 816,529, filed May 28, 1959, now Patent No. 3,078,077.

In conventional carburetors, a float controlled fuel inlet needle valve is employed to regulate the fuel levelin the carburetor fuel bowl. Small dirt particles sometimes interfere with effective operation of the valve, as for example by becoming lodged between mating valve seats which otherwise cooperate to regulate the fuel flow into the fuel bowl. Also the floats require considerable size in order to be effective because of the comparatively low specific gravity of the fuel. In consequence the size of the fuel bowl must be appreciably larger than is otherwise desired.

An important object of the present invention is to provide an improved carburetor which avoids the foregoing objections and in particular to provide a floatless carburetor which does not require a fuel inlet needle valve.

Another object is to provide such a construction including an overflow standpipe in the fuel bowl having an upper opening which determines the maximum fuel level in the bowl. A fuel inlet pump is provided to pump fuel into the bowl at a rate in excess of demand. The excess fuel overflows into the standpipe and is returned to the fuel tank. In order to assure a positive return fuel flow and to overcome adverse grade conditions which prevent the excess fuel from returning to the tank by gravity flow, a scavenging pump is provided in the fuel return line between the overflow standpipe and the tanlc Among other advantages of the above structure, elimination of the necessarily large float enables utilization of a comparatively small fuel bowl closely adjacent the inlet air induction conduits of a multiple barrel carburetor, for example. The small fuel bowl thus located is less sensitive to grade and inertial effects and enables uniform fuel distribution to each of the several induction conduits. Also recirculation of the fuel drives off its more volatile fuel fractions and thereby minimizes some of the problems of the conventional float controlled carburetor, as for example those concerned mation. I

In order to provide adequate fuel during maximum engine speed at wide open throttle, a fuel inlet pump is provided which delivers an excess supply of fuel to the fuel bowl during all operating conditions of the engine. When the throttle is suddenly closed whilethe engine is still operating at high speed, unless some provision is made to the contrary, a major portion of the fuel supplied to the fuel bowl will be recirculated. In general the life of a fuel pump and in particular the life of an engine driven diaphragm type pump, which is preferred for supplying fuel in the quantity required and at a substantially uniform pressure regardless of changes in engine speed, depends upon the quantity of fuel pumped.

For the above reasons, as well as the desirability of conserving power in an automobile engine and of mini mizing'fuel heating by excessive recirculation, another object of the present invention is to provide improved simple and highly effective means for supplying fuel to the fuel bowl in reasonable and safe amounts related to engine requirements.

with vapor for- "ice Another object is to provide a carburetor and diaphragm fuel pump combination of the type described wherein the pump comprises a pumping chamber having a movable diaphragm defining one wall thereof. The pumping chamber is provided with check valve controlled inlet and discharge ports in communication with a fuel tank andwith the fuel bowl'respectively and operative so that during movement of the diaphragm in one direction in an intake 7 stroke to enlarge the volume of the pumping chamber, fuel is drawn from the tank into the pumpingohamber. During movement of the diaphragm in the opposite direction in a pumping stroke, fuel is discharged from the pumping chamber into the fuel bowl. The diaphragm is secured to a plunger arm for actuation thereby. A pumpingspring under compression between the diaphragm and a fixed portion of the pump mechanism yieldingly urges the diaphragm in said opposite direction to cause the pumping stroke. A pivotal arm engageable with a rotating cam driven by the automobile engine to be pivotally oscillated thereby is also engageable with the plunger to move the latter in said one direction against the force of the pumping spring to compress the latter. The pivotal arm is also freely engageable with the plunger so that during the reverse pivotal movement of the arm, the latter will move independently of the plunger and release the diaphragm for spring urged pumping movement in said opposite direction, but will not positively urge movement of the diaphragm in said oppositedirection. In consequence, the pumping force will result entirely from the compressed pumping spring and will be substantially constant regardless of the speed of the engine or of the pivotally oscillated arm.

Other and more specific objects are to provide such a diaphragm pump and carburetor combination having means for varying the pumping stroke of the diaphragm in said opposite direction by a direct linkage with the throttle actuating mechanism, or by pressure actuated means connected with the engine air inlet induction system or with the discharge side of the scavenging pump.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in' the several views.

FEGURE l is a schematic mid-sectional view of a floatless return flow carburetor and pump embodying the present invention showing means actuated by induction conduit pressure downstream of the throttle valve for controlling the diaphragm pumping stroke.

FIGURE 2 is a view similar to FIGURE 1, but showing means actuatedby induction conduit pressure at the venturi throat for controlling the diaphragm stroke.

FIGURE 3 is a view similar to FIGURE 1, but showing means actuated by the scavenging pump discharge pressure for controlling the diaphragm stroke.

FIGURE 4 is a view similar to FIGURE 1, but showing a mechanical linkage with the throttle mechanism for controlling the diaphragm stroke.

-It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawsings, since the invention is capable of other embodiments and of being practiced or carried out in various Ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of descrip.

.tion and not of limitation.

Referring to FIGURE 1, the carburetor shown comprises a cast housing formed to provide an air inlet induction conduit including a ,venturi portion 10 having a restricted venturi 11 at its upper portion and a throttle blade 12 pivotally mounted on a shaft '13 at a lower portion usually referred to as the throttle body. An upper pontion of the casting is formed to provide an air horn 14 adapted to be connected with the usual air filter and opening at its downstream end into the venturi 11 to supply air thereto. The casting portions and 14 are suitably secured together, as for example by screws not shown, and comprise an upper portion of the air inlet and fuel mixing induction system which extends downstream of the throttle valve 12 and discharges into the usual engine cylinders in a conventional manner.

Integral with the casting '19 in the present instance is a fuel bowl casting 15 containing an annular chamber or fuel bowl 16 enclosing a cylindrical standpipe or weir 17 which also serves as an acceleration pump cylinder containing a plunger '18 reciprocable in its lower portion and secured to a plunger shaft 19 for actuation thereby. Where desired the shaft 19 is connected by suitable linkage with a pedal operated accelerator mechanism which controls the opening and closing of valve '12 to operate conjointly therewith. Upon upward movement of plunger 18, fuel is drawn into the lower portion of chamber 17 via conduit 20 in communication with the bowl 16. A suitable check valve illustrated schematically as a ball check element 21 normally seats at the mouth of the duct 2%} opening into the lower portion of chamber 17 to prevent loss of fuel therefrom but is raised from its seat by the fuel flow into chamber 17 on the upstroke of plunger 13. Upon downward movement of plunger is the fuel is forced from chamber 17 into the induction conduit via acceleration fuel conduit 22, ball check valve 23, and nozzle 24 which latter discharges into the induction conduit at a location immediatelyabove the throat of venturi 11. The check valve 23 is schematically illustrated as a ball normally urged by'a spring to a seated position closing nozzle 24 from the interior of chamber 17, the ball being readily movable upward against the tension of its seating spring by the acceleration fuel pressure upon downward movement of plunger 18. The main fuel to the engine is supplied via duct 25 which opens at its lower end through metering port 26 into the fuel bowl 16 and communicates at its upper end with a fuel nozzle 27 having its discharge orifice located within thethroat of venturi :11.

In accordance with the structure described thus far, fuel entering the bowl 16 in excess of engine requirements overflows the upper edge of standpipe 17 which thereby maintains the fuel in the bowl 16 at a predetermined maximum level determined by the effective height of the standpipe 17 without recourse to a float operated mechanism. Fuel is supplied to the bowl 16 from a suitable fuel tank via conduit 28.

A multiple piece fuel pump housing 37 comprising an upper dome 33 and a lower basin 3? cooperate with diaphragms 4t? and 41 respectively to provide an inlet fuel pumping or working chamber 42 and an exhaust fuel pumping or scavenging chamber 43. Springs 44 and 45 disposed between portions of housing 37 and diaphragms 49 and 41 respectively are compressible as described below to urge the former diaphragm upwardly and the latter diaphragm downwardly to effect the pumping strokes for the respective chambers 42 and 43. The upper working chamber 42 comprises a portion of supply duct 28 which communicates upstream of chamber 42 with the fuel tank. Fuel enters and leaves chamber 42 via an inlet port 46 and a discharge port 47 associated with check valves 48 and 49 respectively. Upon downward movement of diaphragm 45 as explained below, fuel is drawn in the direction of the arrow 28a from the fuel tank and through inlet port 46 into working chamber 42. During this operation ball valve 43'is forced from its seat at port 46 by the fuel flow, and ball valve 49 seats at the discharge port 47 to close the latter from the fuel bowl 16. Upon upward movement of diaphragm 48, ball valve 48 is caused to seat at port 46 to close the working chamber 42 from the fuel tank. During this operation, the pressure exerted in chamber 42 unseats ball valve 49 from port 47 and supplies fuel via conduit 23 to the fuel bowl 16. The spaces at the sides of the diaphragms 49 and 41 opposite chambers 42 and 43 respectively are vented to the atmosphere by ducts 50 and 51 to facilitate the pump operation.

Fuel is returned in the direction of arrow 52a from standpipe 17 to the fuel tank via fuel return conduit 52 which includes chamber 43 as a portion thereof. Upstream, the conduit 52 communicates with standpipe 17 at a location above the uppermost limit of movement of plunger 18. The return fuel enters chamber 43 via port 53 and discharges from chamber 43 via port 54. Ball check valves and 56 are associated with ports 53 and 54 respectively, so that upon upward movement of dia-, phragm 41 as described below, ball 56 seats against port 54 to close chamber 43 from the fuel tank. During this operation, ball 55 is unseated from port 53 to open communication between chamber 43 and standpipe 17 and to draw fuel from the latter. Upon downward movement of diaphragm 41, ball 55 is seated against port 53 to close chamber 43 from standpipe 1'7. Simultaneously ball 56 is unseated from port 54 by the pressure in chamber 43 to discharge fuel from the latter in the direction of arrow 52a to the tank. Movement limiting pins in the conduits 28' and 52 associated with the ball valves 48, 49, 55 and 56 prevent undue movement of the balls from their associated ports. Inasmuch as the check valves are well known, these are merely shown schematically and are not discussed in further detail.

Actuation of the diaphragms 40 and 41 is accomplished by driving shafts 57 and 58 connected to these diaphragms and terminating in enlarged heads 59 and 60 respectively. Pivotal levers 61 and 52 are pivoted between their ends at as and d4- respectively, pivot 63 being adjustable as described below and pivot 64- being mounted on a fixed portion of housing 37. Each lever has one end engaged with a rotating eccentric cam 55 mounted on a shaft 66 driven :by the automobile engine. The opposite ends of the levers 61 and 62 are provided with oversized openings 67 and 68 through which the rods 57 and 58 extend freely to enable their relative sliding movement with respect to the levers c1 and 62 until the levers engage the enlarged heads 59 and 69.

Upon operation of the automobile engine, shaft 66 is rotated to turn cam and thereby cause pivoting of levers 61 and 62. Upon clockwise pivoting of lever 61, or counterclockwise pivoting of lever 62, the head 59 or 60 is engaged to pull the associated rod 57 and 53 in the direction to compress the spring 4 or 4-5 as the case might be. Upon counterclockwise pivoting of lever 61 and clockwise pivoting of lever 62, the oversized openings 67 and 68 enable the levers to swing independently of the shafts 57 and 58, whereupon springs 44 and 45 are released to force diaphragms 40' and 4-1 in pumping actions toward the associated dome 38 and basin 39. The pivotal action of levers 61 and 62 merely compresses the springs 44 and 45 alternately, which latter then exert resilient force to effect the pumping action of the associated diaphragms 40 and 41. In consequence, fuel is discharged from chamber 42 at a uniform optimum pressure determined by the force of spring 44. Upon the upward spring urged pumping stroke of diaphragm 40, fuel is discharged via port 47 to fuel bowl 16. All fuel in excess of engine requirements overflows the standpipe 17 and returns by conduit 52 to chamber 43 via port 53, whereuponthe fuel is pumped to the fuel tank by downward spring urged pumping movement of diaphragm 41.

In order to prevent too great an excessof fuel from being pumped to fuel bowl 16 when the engine is operating at comparatively light load, means are provided for limiting the maximum movement of diaphragm 40 during the spring urged pumping stroke. As illustrated in FIG. 1, pivot 63 is mounted on the right end of the comparatively short horizontal leg of a dog-leg lever 69 which in turn is pivotally mounted at its knee at 70 on a fixed portion of the engine, as for example housing 37. A compara tively long leg of lever e9 extends upright from pivot 7t? and is pivotally connected at its upper end at 72 to the outer or right end of a plunger shaft 73. The latter extends slidably in guided relation through a guide and vent hole 74 in the wall of a chamber 75 and is'suitably secured at its inner end within chamber 75 to a ilexi le diaphragm 76 which partitions chamber 75 into two parts. Coil spring 77 interposed between housing 75 and diaphragm 76 resists leftward movement of the latter.

Variations in engine fuel requirements are detected by conduit 78 which connects pressure chamber 75 at the left of diaphragm 75 with the low pressure region of induction conduit It downstream of throttle valve 12. When the engine is operating at light load and throttle valve 12 is partially closed, the low pressure applied through conduit 78 to the left side of diaphragm 7e will cause the latter to be forced to the left against the pressure of spring 77, thereby swing lever 69 counterclockwise about the axis of pivot 70 to raise the pivot 63 and reduce the pumping stroke of diaphragm 4ft. 7

In the converse action, as throttle valve 12 progressively moves toward an open position, the pressure conveyed to the left side of diaphragm 76 by conduit 78 increases, enabling rightward movement of diaphragm 76 in accordance with the force of spring 77. In consequence, lever 69 is pivoted clockwise about the axis of pivot 7 0 to lower the pivot 63 and enable an increased pumping stroke of diaphragm 49. In this regard spring 44 is, illustrated in its uncompressed condition in FIGS. 1-4 and a limited amount of lost motion exists between lever 61 and enlargement 59. Upon lowering of pivot 63, this lost motion is reduced and the amount of compression of spring 44 upon clockwise swinging of lever 61 is thereby increased. Correspondingly the potential compression stroke of diaphragm 4b is increased. Thus with decreased engine load, the pumping stroke of diaphragm ll) is dccreased, the fuel flow pumped via conduit 2% into fuel bowl 116 is decreased, and recirculation of fuel to the bowl 16 is minimized. With increasing engine load, the increased pumping stroke enabled by diaphragm 4d increases the fuel fiow via conduit 28 to fuel bowl 1%.

Although the structure of FIGURE 1 provides means for supplying fuel to bowl 16 at a rate which is a function of engine load, the vacuum induced force below valve 12 is at its maximum at low engine load and progressively decreases as engine load increases. Accordingly at comparatively high engine load when the throttle valve 12 is open fully or nearly so, the vacuum force acting on diaphragm 76 is a minimum. Thus changes in the throttle position result in comparatively low magnitude pressure changes "on diaphragm 76.

Where increased effectiveness of the vacuum induced force at high engine load is desired, a construction such as illustrated in FIGURE 2 is preferred. The general arrangement of the return flow carburetor and pump is the same in FIGURE 2 as in FIGURE 1, so that identical parts are numbered the same in both views. The 'distinc tion in FIGURE 2 over FIGURE 1 is that conduit 73 connects chamber 75 at the right of diaphragm as with the induction conduit adjacent the throat of venturi 11. Housing 75 and plunger 73 are arranged with respect to lever 659 so as to raise pivot 63 and limit the pumping stroke of diaphragm 49 upon clockwise pivoting of lever 69. Upon counterclockwise pivoting of lever 69, pivot 63 is lowered and the pumping stroke of diaphragm ill urged by spring 49 is increased.

Accordingly as engine load increases, the vacuum induced force at the throat of venturi ll increases and becomes a maximum at wide open throttle. The resulting low pressure at the right "of diaphragm as results in rightward movement of diaphragm 76 and plunger 73 against the force of spring 77 to pivot lever 69 clockwise and lower pivot as to increasethe fuel pumping stroke of diaphragm 40. In consequence, as the airflow through venturi throat 11 increases with increasing engine load, the

counterclockwise and raise pivot 53 to decrease the pumping stroke of diaphragm 44 thereby to decrease the fuel flow into bowl I6.

In the FIGURE 2 construction, the vacuum, induced force at the throat of venturi 11 becomes a minimum at low engine load. Accordingly where desired a dual control of the inlet fuel flow as illustrated in both FIGURES l and 2 may be employed to assure adequate operating force during conditions of both high and low engine loads.

FIGURE 3 also illustrates a return flow carburetor and pump as described above wherein corresponding parts are numbered the same. URE l to reduce the pumping stroke of diaphragm 4t upon being pivoted counterclockwise about its pivot 74 and to increase the pumping stroke of diaphragm 4%) upon being pivoted clockwise about the axis 76. Plunger 73 extends slidably through the right side of housing 75 in fiuid sealing engagement therewith at 7 5a. Vent 36 is provided in the left side of housing 75 to facilitate movement of diaphragm 76. Instead of employing the induction conduit pressure to control the movement of diaphragm 76 in accordance with engine load, a conduit 81 connects the upper right side of chamber 75 with the return flow conduit 52 at a location downstream of pumping chamber 43, thereby to regulate the pressure at the right of diaphragm as as a function of the return fuel flow. in order to accentuate the pressure changes in conduit fill, a restriction 82 is provided in conduit'SZ at a location downstream of the latters connection with conduit 81.

In accordance with the structure of FIGURE 3, when engine load and fuel consumption drop, the return flow through conduit 52 normally tends to increase. The increased return fuel flow is indicated by an increased pressure in the portion of conduit 52 between pumping chamber 43 and restriction 82. This pressure increase is transmitted by conduit 81 to diaphragm 76 to urge the latter leftward against the force of spring 77 and cause counterclockise pivoting of lever as to progressively raise pivot 63 and decrease the pumping stroke of diaphragm so. Thus the fuel flow to bowl 316 is reduced and circulation of fuel through the bowl 1% is decreased until the latter fuel flow attains an equilibrium condition determined by the new engine load requirement.

It is also apparent that upon an increase in fuel consumption by the engine, the fuel return flow in conduit 52 will decrease and the pressure in conduit 31 acting on the right side of diaphragm 76 will likewise decrease,

enabling spring 77 to urge diaphragm 76 rightward to pivot lever 69 clockwise and lower pivot 63. The pumping stroke of diaphragm as and the fuel flow to bowl 16 thus increase until the system again reaches the desired equilibrium condition determined by the fuel requirements at the new engine load. The foregoing structure is inde pendent of pressure changes in the induction conduit and depends only upon the rate of return fuel flow in conduit 52, which is thus regulated to' a desired nominal value during all conditions of engine operation.

FIGURE 4 illustrates the return flow carburetor and pumping mechanism as in FIGURE 1 wherein corresponding parts are again numbered the same. instead of controlling the pumping stroke of diaphragm 4% by induction conduit pressure as in FIGURES l and 2,

or by return flow fuel pressure asin FIGURE 3, the.

Lever s9 is arranged as in FIG- However,

cally between guide bosses 56 integral with the carburetor casting and is pivotally connected at 87 to the upper end of a connecting link 88. The lower end of link 33 is pivotally connected at 89 to the outer swinging end of a crank arm 90 keyed to throttle valve shaft 13 to pivot therewith.

Upon pivoting of crank arm 99, as for example by linkage 91 which is suitably connected with crank arm 90 and the customary pedal operated throttle mechanism, valve 12 is opened or closed. When crank arm 9% is pivoted clockwise, throttle valve 12 is progressively opened and link 88 and lever 84, 35 are moved downward to cause pivot pin 71 in groove 83 to swing lever 69 clockwise about its pivot axis 70 and to lower pivot 63. In consequence, upon opening of throttle valve 12 during increased engine load, the pumping stroke of diaphragm 46 and the fuel flow to fuel bowl 16 are increased.

Upon counterclockwise or closing movement of valve 12 with decreasing engine load, link 38 is moved upwardly, lever 69 is pivoted counterclockwise about its pivot axis 70, and pivot 63 is raised to minimize the pump ing stroke of diaphragm 4% and the fuel supply to bowl 16.

I claim:

1. In a carburetor for an internal combustion engine having an air intake manifold system, a fuel bowl, means responsive to the air flow in said manifold system for discharging fuel thereinto from said bowl, a movable-wall type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return means in communication with said chamber to drain fuel therefrom upon overflow of excess fuel from said bowl into said chamber, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, pressure exerting means for yieldingly urging said wall in a pumping stroke, actuating means including follower means operatively associated with said Wall for moving the latter in opposition to said pressure exerting means to effect an intake stroke of said wall upon movement of said actuating means in one direction and for releasing said wall for movement in said pumping stroke upon movement of said actuating means in the opposite direction, said actuation means also including a cyclical cam, said follower means being engageable with Said ca 1 for reciprocation thereby, and adjustable means responsive to said air flow in said manifold system for adjustably controlling the relative positions of said follower means with respect to said cam to increase said intake stroke with increasing air flow.

2. In a carburetor for an internal combustion engine, movable wall type pumping means for connecting a source of fuel with said carburetor, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, resilient means for yieldingly urging said wall in said pumping strokes, a pivotal actuating lever, means operatively connecting said lever and wall for alternately moving the same in said intake strokes in opposition to said resilient means and for releasing said wall for movement in said pumping strokes upon alternate pivoting of said lever in opposite directions, fuel control means for controlling the fuel flow through said carburetor to said engine, and means responsive to operation of said fuel control means for adjusting the pivot axis of said actuating lever to increase the extent of said pumping strokes when the latter means is operated to increase said fuel flow.

3. In a carburetor for an internal combustion engine, movable wall-type pumping means for connecting a 'source of fuel with said carburetor, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, resilient means for yieldingly urging said wall in said pumping strokes, a pivotal actuating lever, means operatively connecting said lever and Wall for alternately moving the same in said intake strokes in opposition to said resilient means and for releasing said wall for movement in said pumping strokes upon alternate pivoting of said lever in opposite directions, the last means providing adjustable lost motion between said lever and wall effective to determine the extent of the resiliently urged pumping strokes, said lost motion being adjustable by adjustment of the pivot axis of said lever, fuel control means for controlling the fuel flow through said carburetor to said engine, and means operatively associated with said fuel control means and lever for adjusting said pivot axis to increase the extent of said pumping strokes upon operation of said fuel control means to increase said fuel flow.

4. in a carburetor for an internal combustion engine having a fuel-air induction conduit, movable wall-type pumping means for connecting a source of fuel with said carburetor, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, resilient means for yieldingly urging said wall in said pumping strokes, a pivotal actuating lever, means opera tively connecting said lever and wall for alternately moving the same in said intake strokes in opposition to said -resilient means and for releasing said wall for movement in said pumping strokes upon alternate pivoting of said lever in opposite directions, and means for varying said pumping strokes comprising means responsive to the pressure in said conduit for adjusting the pivot axis of said actuating lever.

5. In a carburetor for an internal combustion engine having a fuel-air induction conduit, a throttle valve in said conduit for controlling the fuel flow through said carburetor to said engine, movable wall-type pumping means for connecting a source of fuel with said carburetor, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, resilient means for yieldingly urging said wall in said pumping strokes, a pivotal actuating lever, means operatively connecting said lever and wall for alternately moving the same in said intake strokes in opposition to said resilient means and for releasing said wall for movement in said pumping strokes upon alternate pivoting of said lever in opposite directions, and means operatively connected with said throttle valve for adjusting the pivot axis of said lever to increase the extent of said pumping strokes upon the actuation of said throttle valve to increase the said fuel flow.

6. In the combination according to claim 2, said carburetor having an air inlet conduit, said fuel control means including a throttle valve in said inlet conduit for controlling inlet air flow therethrough, and said means responsive to operation of said fuel control means including means operatively connected with said lever and throttle valve for increasing said amplitude upon opening of said throttle valve.

7. In combination, a carburetor for an internal combustion engine, means for connecting a source of fuel with said carburetor, movable wall-type pumping means in the first named means, fuel flow control means for controlling the fuel flow to said carburetor, said pumping means having a reciprocable Wall movable in alternate intake and pumping strokes, pressure exerting means for yieldingly urging said wall in a pumping stroke, actuating means including a follower means operatively associated with said wall for moving the latter in opposition to said pressure exerting means to effect an intake stroke of said wall upon movement of said actuating means in one direction and for releasing said wall for movement in said pumping stroke upon movement of said actuating means in the opposite direction, said actuating means also includg 5 ing a cyclical cam, said follower means being engagenble with said cam to be reciprocated thereby, and means responsive to operation of said fuel flow control means for adjusting the relative positions of said follower means with respect to said cam to increase the extent of said pumping strokes upon operationof said fuel flow Control means to increase said fuel flow.

Refei'ences Cited in the file of this patent UNITED STATES PATENTS 1,722,735 Deland July 30, 1929 Muzzy Ot.-11,'1932 Grifiin et a1 Aug. 11, 1936 Winfield Q. Nov. 15, 1938 Mallory Sept. 2, 1941 Y Udale Oct. 22, 1946 Loftin Feb. 14, 1956 Eberhardt Sept. 22, 1959 

1. IN A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE HAVING AN AIR INTAKE MANIFOLD SYSTEM, A FUEL BOWL, MEANS RESPONSIVE TO THE AIR FLOW IN SAID MANIFOLD SYSTEM FOR DISCHARGING FUEL THEREINTO FROM SAID BOWL, A MOVABLE-WALL TYPE FUEL PUMPING MEANS, INLET CONDUIT MEANS CONNECTING SAID PUMPING MEANS AND BOWL FOR SUPPLYING THE LATTER WITH FUEL UPON OPERATIN OF SAID PUMPING MEANS, MEANS FOR MAINTAINING THE FUEL IN SAID BOWL AT A PREDETERMINED LEVEL COMPRISING AN OVERFLOW WEIR IN SAID BOWL DEFINING AT LEAST IN PART A CHAMBER ADAPTED TO RECEIVE EXCESS FUEL OVERFLOWING SAID WEIR FROM SAID BOWL WHEN THE FUEL IN SAID BOWL ATTAINS SAID PREDETERMINED LEVEL, FUEL RETURN MEANS IN COMMUNICATION WITH SAID CHAMBER TO DRAIN FUEL THEREFROM UPON OVERFLOW OF EXCESS FUEL FROM SAID BOWL INTO SAID CHAMBER, SAID PUMPING MEANS HAVING A RECIPROCABLE WALL MOVABLE IN ALTERNATE INTAKE AND PUMPING STROKES, PRESSURE EXERTING MEANS FOR YIELDINGLY URGING SAID WALL IN A PUMPING STROKE, ACTUATING MEANS INCLUDING FOLLOWER MEANS OPERATUVELY ASSOCIATED WITH SADI WALL FOR MOVING THE LATTER IN OPPOSITION TO SAID PRESSURE EXERTING MEANS TO EFFECT AN INTAKE STROKE OF SAID WALL UPON MOVEMENT OF SAID ACTUATING MEANS IN ONE DIRECTION AND FOR RELEASING SAID WALL FOR MOVEMENT IN SAID PUMPING STROKE UPON MOVEMENT OF SAID ACTUATING MEANS IN THE OPPOSITE DIRECTION, SAID ACTUATION MEANS ALSO INCLUDING A CYCLICAL CAM, SAID FOLLOWER MEANS BEING ENGAGEABLE WITH SAID CAM FOR RECIPORCATION THEREBY, AND ADJUSTABLE MEANS RESPONSIVE TO SAID AIR FLOW IN SAID MANIFOLD SYSTEM FOR ADJUSTABLY CONTROLLING THE RELATIVE POSITIONS OF SAID FOLLOWER MEANS WITH RESPECT TO SAID CAM TO INCREASE SAID INTAKE STROKE WITH INCREASING AIR FLOW. 